Your problem is probably one of the following;
1. You are trying a mode your monitor won't support.
2. Your monitor is out of adjustment.
3. Your monitor is faulty.
Possibly, the card or monitor is not "playing the rules", eg monitor expects
one set of sync rates according to the sync polarities, and the card is sending
out another (unlikely but...)

VGA monitor ID signals

Mike, I don't know if this is related to your problem or not, but IBM
monitors have 3 pins dedicated to a "monitor ID" code, which is available to
the VGA (or 8514/A or XGA) card, and also to the software. OS/2 uses it, for
example, to automatically install the correct display support. The code:

Maybe your projector is not providing the code to tell the VGA that it is
there. If so, you can try modifying the plug.

DISCLAIMER: I know this works for some Sony monitors, which support 1024x768
but don't provide the proper code to the PS/2, so they come up in 640x480.
By changing the plug, the system sees the monitor as high-res-capable, and
configures itself for 1024x768. Whether grounding pins in your plug will
your projector, however, I can't say (although I doubt it).

Does anyone know how the VGA video feature connector operates? I
would like to know which of the pins are inputs, which are outputs,
and which are bidirectional (if any - and how the direction is
selected).

And I assume that pins 1 - 12 are outputs, and 17 - 19
are inputs. Is this correct?

The reason is this - I have a Rombo Media Pro+ video
digitising card. It chroma keys its output into the vga
monitor signal. However, although it is supposed to work
with an ET-4000 with Hi-colour RAMDAC, the colours on screen
behave as if the top 2 bits of colour information are missing,
and red, green, blue signals are swapped around.
Rombo has suggested that this may be due to insufficient
buffering on the feature connector outputs, and is happy to
sell me a buffer device for 50 pounds.
I would rather save about 45 pounds, and build my own. I assume
it would require (for example) a 74F244 buffer IC (or two).

Can anyone help? Any information on the feature connector would
be highly appreciated!

back side

VESA DPMS monitor power management

VESA DPMS is a monitor power managament standard designed for green PC
concept. VESA DPMS defines method how a screen saver program can
put monitor to power save state when it blanks the screen. The signalling
to monitor is handled using normal monitor sync signals: screen saver can
turn one of sync signals (or both) off and the monitor knows from this
that it must turn to power save mode.

VESA DPMS power states:
NORMAL STANDBY SUSPENDED OFF
H-sync On Off On Off
V-sync On On Off Off
Power level 100% 80% <30W <8W
Recovery time N/A ~1 sec ~4 sec ~8-20 sec

NUTEK monitor power management

NUTEK is a Swedish standard for monitor power management so that
screen saver program can turn monitor to power save mode when
computer is not used for a while. NUTEK works using the following
pronciple: when the picture signa coming to the monitor has been totally
black for lomg enough, the monitor turns to power save mode. When
there is other than just black coming to monitor, then the monitor turns
back to normal operation.

VESA modes

This list is not complete list of SuperVGA modes standardized by VESA.
For complete documentation check
VESA VBE standard.